The present invention relates generally to inflators for use in inflatable occupant restraint systems in motor vehicles and, more particularly, to inflators that do not incorporate a filter for removal of particulates from combustion gases and cooling of the gases.
Installation of inflatable occupant restraint systems, generally known as “airbags,” as standard equipment in all new vehicles has intensified the search for smaller, lighter and less expensive restraint systems. Accordingly, since the inflator used in such systems tends to be the heaviest and most expensive component, there is a need for a lighter and less expensive inflator.
A typical inflator includes a cylindrical steel or aluminum housing having a diameter and length related to the vehicle application and characteristics of a gas generant propellant contained therein. Inhalation by a vehicle occupant of particulates generated by propellant combustion during airbag activation can be hazardous. Thus, the inflator is generally provided with an internal, more rarely external, filter comprising one or more layers of steel screen of varying mesh and wire diameter. Gas produced upon combustion of the propellant passes through the filter before exiting the inflator. Particulate material, or slag, produced during combustion of the propellant in a conventional system is substantially removed as the gas passes through the filter. In addition, heat from combustion gases is transferred to the material of the filter as the gases flow through the filter. Thus, as well as filtering particulates from the gases, the filter acts to cool the combustion gases prior to dispersal into the airbag. However, inclusion of the filter in the inflator increases the complexity, weight, and expense of the inflator.